The sun’s corona is weirdly hot, and Parker Solar Probe rules out one explanation

By diving into the sun’s corona, NASA’s Parker Photo voltaic Probe has dominated out S-shaped bends within the sun’s magnetic area as a explanation for the corona’s searing temperatures, in accordance with College of Michigan analysis published in The Astrophysical Journal Letters.

The sun’s crown-like environment might be 200 instances hotter than the sun’s floor, regardless of being farther away from the last word supply of warmth on the sun’s core. How the corona‘s warmth seemingly defies physics has stumped scientists for many years, but it permits the sun’s scorching soup of charged particles, or plasma, to maneuver quick sufficient to flee the sun’s gravitational pull and engulf our solar system because the solar wind.

To unravel the thriller, NASA constructed the Parker Photo voltaic Probe to dive into the corona and discover its heat source. The spacecraft is supplied with a set of devices designed by Justin Kasper, U-M professor of local weather and space sciences and engineering, to immediately measure the density, temperature and circulation of the corona’s plasma.

When it first approached the sun, the probe detected tons of of S-shaped bends within the sun’s magnetic field—named switchbacks in reference to how they briefly reverse the route of the magnetic area—together with 1000’s of shallower bends. To some scientists, the switchbacks appeared like promising sources of warmth to the corona and solar wind. Their extreme S-shape bend saved lots of magnetic energy, which doubtless launched into the encompassing plasma because the switchbacks traveled by way of space and ultimately straightened out.

“That power has to go someplace, and it may very well be contributing to heating the corona and accelerating the solar wind,” mentioned Mojtaba Akhavan-Tafti, U-M assistant analysis scientist of local weather and space sciences and engineering and the corresponding creator of the research.

However to warmth the corona, switchbacks want to maneuver by way of it, so studying the place switchbacks kind is vital for understanding their affect on the corona’s temperature. After poring over the information from the Parker Photo voltaic Probe’s first 14 laps across the sun, the analysis crew found that whereas the S-shaped bends are frequent within the solar wind close to the sun, they’re absent contained in the corona.

Scientists nonetheless cannot agree on what causes switchbacks. Some assume that the magnetic area is bent by turbulence within the solar wind past the corona. Others assume that switchbacks begin their journey on the floor of the sun, when churning magnetic field lines and loops explosively collide and mix into bent shapes.

The research’s outcomes rule out the latter speculation. If switchbacks had been shaped by colliding magnetic fields on the floor of the sun, they must be much more frequent contained in the corona. Nevertheless, Akhavan-Tafti thinks magnetic collisions may nonetheless play some oblique position within the origins of switchbacks—and the heating of the corona.

“Our concept may fill the hole between the 2 faculties of thought on S-shaped switchback technology mechanisms,” Akhavan-Tafti mentioned. “Whereas they have to be shaped exterior the corona, there may very well be a set off mechanism contained in the corona that causes switchbacks to kind within the solar wind.”

When magnetic fields collide on the sun’s floor, they vibrate like plucked guitar strings and ship waves alongside the magnetic fields into space. On the identical time, the power from the collisions creates very quick streams of plasma within the solar wind.

Akhavan-Tafti thinks the quick plasma distorts the magnetic waves into switchbacks within the solar wind. If a few of these waves dissipate contained in the solar environment earlier than turning into switchbacks, they may additionally play a component in heating the corona.

“The mechanisms that trigger the formation of switchbacks, and the switchbacks themselves, may warmth each the corona and the solar wind,” he mentioned.

There at present is not sufficient information to favor triggers on the sun’s floor over turbulence within the solar wind as the reason for switchbacks, nevertheless.

“Parker Photo voltaic Probe’s upcoming journeys into the sun, as early as December 24, 2024, will gather extra information even nearer to the sun. We’ll use the information to additional take a look at our speculation,” Akhavan-Tafti mentioned.